Episodic disc accretion in the halo of the 'old' pre-main-sequence cluster η Chamaeleontis

Simon J. Murphy; Warrick A. Lawson; Michael S. Bessell; Daniel D.R. Bayliss

doi:10.1111/j.1745-3933.2010.00992.x

Episodic disc accretion in the halo of the 'old' pre-main-sequence cluster η Chamaeleontis

Simon J. Murphy^*
, Warrick A. Lawson
, Michael S. Bessell
, Daniel D.R. Bayliss

^*Corresponding author for this work

Research output: Contribution to journal › Letter › peer-review

21 Citations (Scopus)

Abstract

We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ~8 Myr η Chamaeleontis open cluster. During six months of observations, both stars exhibited variations in their Hα line profiles on time-scales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disc. We derive an accretion rate of ~10^-8.7 M_⊙ yr^-1 for this event, with a rate of ~10^-10.6 M_⊙ yr^-1 in quiescence. Episodic accretion like that observed here suggests existing surveys of accreting weak-lined T Tauri stars in young clusters are likely incomplete and that gas dissipation time-scales calculated from the fraction of accreting objects are underestimates.

Original language	English
Pages (from-to)	L51-L55
Journal	Monthly Notices of the Royal Astronomical Society: Letters
Volume	411
Issue number	1
DOIs	https://doi.org/10.1111/j.1745-3933.2010.00992.x
Publication status	Published - Feb 2011

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@article{ef07b00df22b4abe91a2f9137974769f,

title = "Episodic disc accretion in the halo of the 'old' pre-main-sequence cluster η Chamaeleontis",

abstract = "We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the \textasciitilde{}8 Myr η Chamaeleontis open cluster. During six months of observations, both stars exhibited variations in their Hα line profiles on time-scales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disc. We derive an accretion rate of \textasciitilde{}10-8.7 M⊙ yr-1 for this event, with a rate of \textasciitilde{}10-10.6 M⊙ yr-1 in quiescence. Episodic accretion like that observed here suggests existing surveys of accreting weak-lined T Tauri stars in young clusters are likely incomplete and that gas dissipation time-scales calculated from the fraction of accreting objects are underestimates.",

keywords = "Accretion, accretion discs, Open clusters and associations: individual: η chamaeleontis, Stars: low-mass, Stars: pre-main-sequence, Techniques: spectroscopic",

author = "Murphy, \{Simon J.\} and Lawson, \{Warrick A.\} and Bessell, \{Michael S.\} and Bayliss, \{Daniel D.R.\}",

year = "2011",

month = feb,

doi = "10.1111/j.1745-3933.2010.00992.x",

language = "English",

volume = "411",

pages = "L51--L55",

journal = "Monthly Notices of the Royal Astronomical Society: Letters",

issn = "1745-3925",

publisher = "Oxford University Press ",

number = "1",

}

TY - JOUR

T1 - Episodic disc accretion in the halo of the 'old' pre-main-sequence cluster η Chamaeleontis

AU - Murphy, Simon J.

AU - Lawson, Warrick A.

AU - Bessell, Michael S.

AU - Bayliss, Daniel D.R.

PY - 2011/2

Y1 - 2011/2

N2 - We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ~8 Myr η Chamaeleontis open cluster. During six months of observations, both stars exhibited variations in their Hα line profiles on time-scales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disc. We derive an accretion rate of ~10-8.7 M⊙ yr-1 for this event, with a rate of ~10-10.6 M⊙ yr-1 in quiescence. Episodic accretion like that observed here suggests existing surveys of accreting weak-lined T Tauri stars in young clusters are likely incomplete and that gas dissipation time-scales calculated from the fraction of accreting objects are underestimates.

AB - We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ~8 Myr η Chamaeleontis open cluster. During six months of observations, both stars exhibited variations in their Hα line profiles on time-scales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disc. We derive an accretion rate of ~10-8.7 M⊙ yr-1 for this event, with a rate of ~10-10.6 M⊙ yr-1 in quiescence. Episodic accretion like that observed here suggests existing surveys of accreting weak-lined T Tauri stars in young clusters are likely incomplete and that gas dissipation time-scales calculated from the fraction of accreting objects are underestimates.

KW - Accretion, accretion discs

KW - Open clusters and associations: individual: η chamaeleontis

KW - Stars: low-mass

KW - Stars: pre-main-sequence

KW - Techniques: spectroscopic

UR - https://www.scopus.com/pages/publications/79952481531

U2 - 10.1111/j.1745-3933.2010.00992.x

DO - 10.1111/j.1745-3933.2010.00992.x

M3 - Letter

SN - 1745-3925

VL - 411

SP - L51-L55

JO - Monthly Notices of the Royal Astronomical Society: Letters

JF - Monthly Notices of the Royal Astronomical Society: Letters

IS - 1

ER -

Episodic disc accretion in the halo of the 'old' pre-main-sequence cluster η Chamaeleontis

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